Praise be to Allah.
The reward for offering iftaar to one who is fasting is great as the Prophet (peace and blessings of Allaah be upon him) said: “Whoever gives iftaar to one who is fasting will have a reward like his, without that detracting from the reward of the fasting person in the slightest.” Narrated by al-Tirmidhi, 708l classed as saheeh by al-Albaani in Saheeh al-Targheeb wa’l-Tarheeb, 1078. See also Question no. 12598.
This reward is earned by everyone who gives iftaar to one who is fasting. It is not subject to the condition that the fasting person be poor, because this is not a kind of charity, rather it is a kind of a gift, and a gift is not subject to the condition that the recipient be poor. Rather it is acceptable to give gifts to both rich and poor.
With regard to the invitations whose purpose is to compete and show off, they are something blameworthy and the one who does this will not have any reward for this action, so they are depriving themselves of a great deal of good.
The person who receives such an invitation should not attend or take part in them, rather he should excuse himself. Then if he is able to advise the one who does that, in the nicest manner that is most likely to be accepted, that is good. He should avoid speaking directly, and use subtle words and speak in general terms that are not directed at any specific person.
For kind and gentle words and good manners, and avoiding harsh words, are among the means of causing advice to be accepted. The Muslim is keen that his fellow-Muslim should accept the truth and act upon it.
The Prophet (peace and blessings of Allaah be upon him) used to do that. Some of his companions did things that the Prophet (peace and blessings of Allaah be upon him) denounced, but he did not confront them with that, rather he would say, “What is wrong with people who do such and such…?”
This manner of speaking should achieve the desired purpose.
And Allaah knows best.